What is a formula of Potassium Sulfate?

First, look at the Periodic Table. Potassium is in group 1 so has a +1 charge, Li⁺Sulphates always have a -2 charge, SO4 ^2-Now combine two ions together so we can get a neutral compound. We have +1 charge on Li ion and -2 charge on SO₄ ion. Therefore, we need two Li+ ions for one SO₄ ²-Now the charges cancel out and we have a neutral salt Li₂SO₄